This invention concerns a process for triggering side airbags of a passive safety device for motor vehicles, which additionally comprises a driver as well as a passenger airbag, a collision sensor located centrally inside the motor vehicle for detecting head-on and side collisions, and left-hand and fight-hand side collision sensors, as well as a control unit evaluating the sensor signals generated by these collision sensors; and, for evaluating the force of a side collision impact, threshold values are specified for the sensor signals of the centrally located collision sensor as well as for the sensor signals of the side collision sensors; and a collision signal will be generated whenever a sensor signal exceeds the lowest threshold value specified.
An occupant protection system for motor, vehicles as a rule consists of an airbag triggering device designed as a control unit comprising four output stages for driving the driver and passenger airbags, as well as the respective belt tensioners for driver and passenger. However, these airbags protect vehicle occupants only in the event of a head-on collision of the vehicle, but not in the event of a side collision. It was proposed therefore to fit an airbag--a so-called side airbag--in the area of the vehicle door in order to restrain the side movement of vehicle occupants. Due to the short deformation path in the event of a side crash, these side airbags require a short triggering time of less than 5 msec; therefore, in addition to the existing collision sensor located centrally inside the motor vehicle for detecting front and side collisions, two extra sensors will be required, all to be located in the door area. Moreover, these additional external sensors are also required because the acceleration signal in the central collision sensor, generated by the crash, cannot yet be evaluated within the required triggering time due to the greater distance to the force input point; at the time of the triggering time required, this acceleration signal will not yet have reached the central area of the vehicle at full amplitude.
Furthermore, it is generally known that before any triggering of a driver or a passenger airbag not only the sensor signals of the central acceleration sensor need to be evaluated; it is also necessary to take the status of a mechanical safety switch into account which mechanical safety switch has an effective action direction parallel to the direction of vehicle travel.